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MG MGB Technical - Clutch Problem

I cannot engage the clutch in my 79 B. I checked the clutch master cylinder resrvoir and found it to be about 1/2 inch low. I filled it to the neck but the push rod is moving back and forth with no resistance and I cannot shift gears. Does this indicated that the clutch master cylinder needs to be replaced? The clutch disc,pressure plate and release bearing were replace about 3K miles ago.Also the slave cylinder has been replace within the past 5K miles.

I would like to attempt this repair by myself and would appreciate any technical advice as to what parts I should order and any installation advice,

Thanks, Davy Crocker
Davy Crocker

The fluid must have gone somewhere. If the
slave is ok, check the hose to the slave -- these
often go bad, especially the aftermarket rubber
ones. Check for clutch MC leaks on the clutch pedal
and from the reservoir itself.

If the system wasn't bled properly, there could be
a lot of air in it which results in no resistance
in the pedal, even with fluid in the MC reservoir.

Check all components for leaks first, and replace
as needed, then try bleeding with a pressure bleeder
(like gunson's eezibleed.) If the clutch MC is
old, I would just replace it and not waste time
rebuilding.
Ronald

When you pump the clutch pedal the slave piston should move about 1/2". However it needs the resistance of the clutch or some other spring to force the slave back, without that 3 or 4 pumps of the pedal will be enough to push the slave piston right out of the cylinder.

Check the travel first. If the slave is not moving at all or is moving back and fore much less than 1/2" it needs bleeding at least if not work on the cylinders/hose. If you are getting the correct travel, or if the pistion is moving out but not back in, then the problem is inside the bell-housing.
Paul Hunt

...and if there was a big "Q-H" on the box your new clutch components came in, you can almost bet something happened inside the bell housing.
Ken Lessig

When you push the clutch pedal in, you should be able to see a slight level change when looking into the top of the cylinder (regardless of whether the rest of the system is full of air). If this level change isn't happening, then there's something up with your master cylinder.

Did this fault appear suddenly? I'm thinking a rubber part has failed inside the M/C and it's not moving any fluid, but it's been a while since I took one apart.

ttfn,
--
Olly S
Oliver Stephenson

Hmmm, push clutch pedal while peering in master cylinder ...

Not as difficult as while 'peeing' in master cylinder I suppose.
Paul Hunt

Heehee :o)

I usually use a stout screwdriver braced against the pedal pivot bar to lever the M/C rod and pedal in rather than having a very long leg with six knees...

--
Olly
Oliver Stephenson

"..and if there was a big "Q-H" on the box your new clutch components came in, you can almost bet something happened inside the bell housing."

Is this a reference to a particular manufacturer? Is it right to always use a Borg and Beck replacement?
Richard Atkinson

Dave, with the clutch master only 1/2 inch low your clutch should still work. Unless msomone put in some DOT 3 fluid then the rubber in the master is gone.

First have a friend pushe the clutch down while watching the slave. If the slave moves its time to pull the engine and look at the clutch itself.

Second if the slave does not move fluse the entire system with LMA GT+4 fluid. If still no replace the master.

Doug
Doug Gordon

This thread was discussed between 19/05/2002 and 23/05/2002

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